I have 10 in a 220 gal but I plan on downsizing. They seem fine aggression wise and in fact I have 3 breeding pairs out of the 10, but the problem comes down to water quality. In order to keep my params at an acceptable level I need to do a 50% water change every 2-3 days. So I plan on downsizing to just 6 (the 3 pairs).
